Commutator and method of making same



Aug. 1, 1950 M. A. ISAACSON 2,516,880

' COMMUTATOR AND METHOD OF MAKING SAME Filed larch 27, 1946 2Sheets-Sheet l ('7 (8 rd (6 r N m w 9 0 o LL ILL L E LL LL. LL

.0 m Q N INVENTOR. d E BY MAX A.ISAACSON N LL 4M ATTORNEY M. A. ISAACSONQOMMUTATQR METHOD OF MAKING SAME Aug. 1, 1950 2 Sheets-Sheet 2 FiledMarch 27, 1946 N M0 N5 m m A B A X A M svm w ATTORNEY Patented Aug. 1,1950 ooMMUTAToR AND METHOD OF MAKING SAME Max A. Isaacson, Dayton, OhioApplication March 27, 1946, Serial No. 657,390

8 Claims.

This invention relates to'commutators, to more or less continuous stockfrom which commutators maybe cut, and to methods of producing suchcommutators and stock.

Among the objects of the present invention is the production ofcommutators of novel type, particularly commutators useful for smallmotors.

Further objects include the production of commutator stock from whichcommutators, particularly of small size, may be readily cut or produced.

Still further objects of the invention include the production of suchcommutators and stock by simple and economical procedures.

Still further objects and advantages of the present invention willappear from the more detailed description set forth below, it beingunderstood that this more detailed description is given by way ofillustration and explanation only, and not by way of limitation, sincevarious changes therein may be made by those skilled in the art, withoutdeparting from the scope and spirit of the present invention.

In connection with that more detailed description there is shown in theaccompanying drawmgs,

Figure 1, representing a side view of the assembly rod, and Figure 1a anend view thereof; in

Figure 2, a form of elongated commutator segment bar that may beutilized in carrying out the present invention, in side view thereof,and Figure 2a and Figure 2?) being respective end views; in

Figure 3, a sheet of insulation material from which insulation laminamay be cut, one of the laminations at Figure 3a, and an end elevation ofthe sheet at Figure 3b; in

Figure 4, an assembly of laminations of the kind shown in Figure 3,assembled on the assembly rod of Figure 1, as side view partly insection being shown, while an end view is shown in Figure 4a; in

Figure 5, a side view of the rod or wire used in the assembling of suchcommutator structure, with an end view shown at Figure 5a; in

Figure 6, an assembly of commutator segment bars, and insulationlaminations, partly in section, with respective end views at Figure 6aand 6b; in

Figure 7, a side view of the finished commutator stock with an end viewat Figure 7a; and in Figures 8a and 8b, side and end views respectivelyof a commutator cut from the stock of Figure '7.

The present invention is thus concerned with the production ofcommutators, particularly of small size for use in small motors andcommu tator stock from which such commutator elements may be cut orformed, and to the methods of producing such commutators and commutatorstock. The invention is .particularly concerned with utilizing a core ofinsulating material carrying peripheral slots therein in which elongatedcommutator segment bars are inserted and fixed in position to producecommutator stock from which individual commutators, particularly when ofsmall size, may be readily formed. In the production of such stock,there are desirably uti lized' elongated commutator segment bars as setlongitudinally of the bar for purposes herein-' after set forth. Aprojection 4 extends outwardly from such face contacting portion 2 andas shown,

is desirably provided with separate leg portions 5, 5, between which isprovided a groove or channel ortion 5. One end 1 of the commutatorsegment bar I may be reduced in size for purposes hereinafter set forth.

The commutator stock is desirably built up from a core of insulationmaterial provided with peripheral slots formed between projections ofsuch material. In the most desirable form of the invention, suchinsulating core is produced from laminations of insulation material. Inthis event a sheet 8 of desired insulating material is employed fromwhich a series of insulating laminations 9 are stamped or cut in anydesired way, each of the laminations having a central opening I0 toenable assembly of the laminations on an assembly rod, the laminationseach being provided with peripheral slots ll, separated by projections12.01" the insulation material between the slots II, II. As shown theslots II are desirably dovetailed. This insulation material used for theproduction of the insulation laminations or where an unlaminatedmaterial is employed, for the laminated core itself, may be of anydesired insulation material, such as formica or a linen or fiber base ofany type impregnated with insulating ma terial such as Bakelite, etc.

Where the insulated core is produced from such laminations, a rod l3having threaded ends l4,

' I4 is provided and on such rod a series of steel laminations 9', 9 ofsubstantially the same shape and size (Figure 4-1) as the insulatinglaminations 8, 9 are placed, and then a, series of the laminations 9, 9are mounted with the slots H and projections ll! of the laminationsbeing aligned 3 and held in position on the rod l-3 by means of nuts I5,[5.

In the channels formed by the aligned slots 1 l, a wedging element suchas wire [6 of steel or other material, desirably harder than that ofwhich the elongated commutator segment bar is composed, is placed ineach of said slots at the base thereof as shown in Figure 6a, and anelongated commutator segment bar I is then placed with the projection 4thereof entering such slot II. Th number of slots employed determinesthe number of elongated commutator segment bars which are employed,there being one such bar for each channel formed by the aligned slots.While five are shown in the drawing, any number more or less than fivemay be utilized. .As shown in Figure 6, after the parts have beenassembled in this way, a sleeve or spring fingers I! may be utilized tohold the parts in assembled relation. The assembly as shown in Figure 6is subjected to a rolling or other pressing operation to force the barsinwardly toward the axial center of the laminations to seat the bars onor in the aligned laminations with the brush contacting desirablyarcuate faces 2, 2, forming a peripheral series of commutator segmentsheld in position by the legs 4 within the slots ll. During suchoperation where the bars are thus forced into position, a wire is ineach of the slots ll serves to spread the leg portions 5, 5 within the 1a number of rollers corresponding to the number of bars utilized inproducing such commutator stock. Such rollers may be provided with anannular ridge or projection which fits into each of the, grooves 3carried on each of the bars i for the purpose of centering the elongatedbar in the slot II. By providing the wire I6 with a rounded upper face19 and a concave lower portion 20, a rigid structure is readilyproduced. The wire should desirably have a width less than that of theslot 1 I but sufficient so that the legs 5, 5 on the projection 4 of thebar I are spread to bite into the formica or other insulation material.The form of wire l6 shown is desirably used but any other form may beemployed. While a wire round in cross-section could be employed, it ismore desirable to make it of the sectional contour shown inFigure 5a inorder to avoid .unnecessary bitinglin'to the formica or other insulationmaterial employed.

The reduced ends 1 of the commutator bars enable the assembly asshown inFigure 6 the more position by the legs 5, 5 on the projection 4 of thecommutator segment bars being spread by the wire [6 as the rolling takesplace. Such stock, of course, carries the grooves 3, 3 in each of thecommutator segment bars, while the segment bars are themselves separatedfrom each other by spacesZl, 21. Only thatportion of the stock producedwith insulating laminations is used to produce commutators.

From such commutator stock as shown in Figure '7, individual'commutatorsmay be cut of the desired length by cutting through the stock materialas indicated at 22 to produce the individual commutator 23. At the sametime or in any desired order with relation to such cutting operation, aportion of the metal may be cut or removed or ground from the commutator23 leaving a riser 25 at the end thereof with the grooves 3, 3 therein,such grooves, however, having been removed from the brush contactingface 24 of the commutator '23. Such grooves as are retained in the riserportion .25 of the commutator element 23 may be utilized for electricalconnection.

The operations including assembly and production of the continuouscommutator stock of any desired length may be readily carried out, andcommutator elements .removed from such stock of any desired length bysimple operations.

A number of modifications alon any desired lines may be utilized in thisconnection. While the laminations are'shown provided with a centralopening ill .for assembly, the laminations may be produced without anysuch central opens readily to be passed into and between the shapingrolls that are employed. The length of the reduced ends I correspondsapproximately to the length of the stack of steel laminations 9' .as,shown in Figure 4 and Figure 6. "The interlock bars from spreadingradially outwardlyfrom the,

core after passing through the rollers. Inaddition, the steellaminations give a rigid end to the commutator stock to enable it morereadily tobe handled and manipulated.

The result of the rolling or pressingoperation is to produce vacommutator stock asshown in Figure 7, having a series ofelongated-commuter tor segment bars. I, carriedperipherally abouttheinsulating core 9, the bars being heldrigidly in,

ing, and the laminations assembled by stacking in any desired way. Forthis purpose if desired, a number of wires corresponding to the numberof slots in the laminations'may be utilized in spaced parallel relationto receive and stack the lamina tions. .Such wiresmay be tensioned to.give them suflicient rigidity when used'as .a supporting and stackingmedium. Further the placing of the elongated commutatornsegment bars inthe slots of the laminations and over the tensioned wires providesfurther and sufficient rigidity to the stack to enable them to be passedthrough .the rollers of the machine that permanently staples the copperbarsin position.

Further the slots H; of the laminations orof an unlammated core need notbe dovetailed but may be parallel and radially arranged. The wire l6 inthe .slots will cause the fins of the inserted portion of the legs ofthe elongated commutator segments bars to spread and penetrate into thematerial of the laminations when suificient pressure is applied to thecommutator segment bars asfthey pass through the rollers.

If the laminationsiare madeof material that is sumciently rigid, thewires themselves can be eliminated but desirably in this case .a centralassembly rod such as that shown at 13 is employed; I

The grooves 3 .on the .elongated commutator segmentbar provide a numberof purposes: they serve to centralize the bars bycooperation with a beadon the rollers during the assembly and they provide a slot for receivingthe wire terminalsof a coil of the armature thus eliminating thenecessity for slotting the commutator for this purpose after thecommutator element is fabricated. p

This feature of utilizing a groove in the-.commutator may be appliedtoconventional commutators formed as punchings from an elongated copperbar. I

.The commutator stock emerges from the rolls or other pressing operationin condition as a finished assembly from which the necessary commutatorelements may be cut or removed as desired. The commutator segmentelements are spaced from each other. If desired the finished assemblymay be passed through the rollers a second time to get a closing ineffect in which event the ridge on the roller may be positioned betweenthe bars to produce a better spacing of the bars; but such secondrolling operation is not essential.

If desired the commutator bars may be coated with an insulation varnishsuch as Formvar or any other insulation material coating or varnish orthey may be clipped in an insulation composition so that when assembledthe bars themselves are electrically insulated from each other. Or theslots between the bars may be filled with an insulation varnish such asSterling varnish or any analogous material either before or afterassembly. It is also possible to insert elongated thin strips of fiberinsulation material or any other analogous material between the bars atthe time that they are assembled and before the rolling operation sothat during the process of rolling, such fiber insulation materialbetween the bars becomes incorporated into the assembly. Or if desired awire may be inserted in the spaces between the bars and after rolling,such wire may be removed to leave the space between the bars,

The present invention enables a very simple operation to be carried outto produce commutator stock material and commutators quite eco nomicallywithout requiring extensive finishing and cleaning operations.

Having thus set forth my invention, I claim:

1. commutator stock from which a number of commutator elements may beformed by cutting transversely through the stock, said stock comprisingan elongated central core of insulating material having a series ofperipheral slots therein the core length being sufficient to provide anumber of commutators, each slot carrying an elongated commutatorsegment bar of length sufficient to provide a number of commutators,each bar having an outer brush contacting portion and inwardlyprojecting legs, the legs of each bar lyin intermediate the ends of thebar, the legs of each bar being anchored within a single slot only, anda wedging element in each slot to wedge he legs within such slot to holdeach bar individually in a single slot in position on the core.

2. commutator stock as set forth in claim 1, in which each commutatorsegment bar is provided with a longitudinal groove therein.

3. Commutator stock from which a number of commutator elements may beformed by cutting transversely through the stock, said stock comprisingan elongated central core of insulating material having a series ofperipheral slots and projections the core length being sufficient toprovide a number of commutators, each slot carrying a wedging elementwithin the slot at the base thereof engaging the innermost wall of theslot and an elongated commutator segment bar of length sufficient toprovide a number of commutators, each bar having an outer brushcontacting portion and inwardly projecting legs, the legs of each barlying intermediate the ends Of the bar, the legs of each bar beinganchored within a single slot only by said wedging element and inpiercing engagement with the sides of said projections to hold each barin a single slot individually in position on the core.

4. Commutator stock from which a number of commutator elements may beformed by cutting transversely through the stock, said stock comprisingan elongated central core of insulating material having a series ofperipheral slots and projections the core length being sufiicient toprovide a number of commutators, spaced elongated commutator segmentbars of length sufficient to provide a number of commutators havinginwardly projecting legs intermediate the Width of the bars and disposedwithin said slots, the legs of said bars being wedged in said slotsagainst walls thereof by a wedging element engaging walls of the slotand in pressure contact relation with the sides of said projections tohold the bars in position on the core.

5. A commutator comprising an elongated central core of insulatingmaterial having a series of peripheral slots therein, each slot carryinga wedging element within the slot at the base thereof engaging theinnermost wall of the slot an elongated commutator segment bar, each barhaving an outer brush contacting face and inwardly projecting legs, thelegs of each bar lying intermediate the ends of the bar, the legs ofeach bar being anchored within a single slot only, and a wedging elementin each slot to wedge the legs within such slot to hold each barindividually in a single slot in position on the core.

6. A commutator comprising an elongated central core of insulatingmaterial having a series of peripheral slots therein, a wire within eachslot at the base of the spot engaging the inner most wall thereof, eachslot carrying an elongated commutator segment bar, each bar having anouter arcuate brush contacting face and inwardly projecting legs, thelegs of each bar lying intermediate the ends of the bar, the legs ofeach bar being anchored within a single slot only, and a wedging elementin each slot to wedge the legs within such slot to hold each barindividually in a single slot in position on the core.

7. A commutator as set forth in claim 5, in which the outer brushcontacting face is provided with a longitudinal groove intermediate thewidth thereof.

8. A commutator segment bar comprising an elongated bar of a length toprovide a number of commutator elements, said bar having a body portioncarrying an elongated outer brush contacting arcuate face portionthereon, said body portion having a longitudinal projecting anchoringbifurcated leg portion intermediate the width thereof and extending forthe length of the bar, and a longitudinal groove in the arcuate baseportion intermediate the width thereof extending the length of the bar.

MAX A. ISAACSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 840,451 Fuld Jan. 1, 19071,319,988 Blumberg Oct. 28, 1919 1,421,734 Sparks July 4, 1922 1,641,414Critchfield Sept. 6, 1927 1,677,936 Thordarson July 24, 1928 1,989,955Van Patter Feb. 5, 1935 2,104,141 Stevens Jan. 4, 1938 FOREIGN PATENTSNumber Country Date 196,726 Great Britain May 3,1923

